Magnetic field sensing elements can be used in a variety of applications. Often, a magnetic field sensing element is used to detect motion (e.g., rotation) of an object, such as a gear or ring magnet. A magnetic field affected by motion of the object may be detected by one or more magnetic field sensing elements, such as Hall effect elements and/or magnetoresistance elements, which provide a signal representing the detected field. Motion of the object may, for example, result in variations in an air gap between the object (or target features of the object) and the magnetic field sensing elements. This may result in variations in the magnetic field as detected by the magnetic field sensing elements and the signals they produce. The signals can be processed to detect position, proximity, speed and/or direction of motion of the object, for example.
Various parameters characterize the performance of magnetic field sensing elements and circuits or sensors that use magnetic field sensing elements. These parameters include sensitivity, which corresponds to a rate of change in a resistance of a magnetoresistance element or a change in an output voltage from a Hall effect element in response to a change in the detected magnetic field. The parameters also include linearity, which is a measurement of how linear the output of the magnetic field sensing element is in response to a linearly changing magnetic field.